Firearms

ABSTRACT

A firearm is provided which has a barrel including a bore having helical grooves and lands between said grooves, and a detachable chamber comprising a tubular body having an inner diameter equal to the diameter of the bore across the lands defined by the helical grooves, one end of the tubular body abuting against the base of the barrel, and the other end having an annular recess adapted to receive and retain a peripheral flange at the rear end of a projectile adapted to be fired from the firearm.

United States Patent [1 1 lnfantino Nov. 5, 1974 FIREARMS 1,191,3577/1916 Snyder 42/78 1751 Inventor: Osvaldo Csar famine, 3332? $1312$3323.;';;;1::3"":::::"""iji'z'zffl Aires, Argentina v [73] Assignee:Direceion General de lnvestigacion y P i E i B j in A, BorchcitDeSalTOllO Mini5teli0 de Assistant Examiner-C. T. Jordan Defensakepubhtca Argentina, Attorney, Agent, or FirmLerner, David. LittenbergBuenos Aires, Argentina & Sam el {22] Filed: July 6, 1972 Appl. No.:269,325

Foreign Application Priority Data July 6, 1971 Argentina 236638 US. Cl.42/76 R, 42/78 Int. Cl. F4lc 21/12 Field of Search 42/76 R, 76 A, 77, 78

References Cited UNITED STATES PATENTS ll/l885 Wheeler 42/77 [57]ABSTRACT 4 Claims, 4 Drawing Figures FIREARMS This invention refers to adetachable chamber for a firearm having a barrel with a helicallygrooved bore, and more particularly, to a chamber for firing theballistic, self-propelled projectile described and claimed in co-pendingpatent application filed on Oct. 18, 1971 No. 189,905.

The invention is also concerned with a firearm including said chamber.

The projectile described in the above-mentioned patent application, iscapable of being totally expelled through the bore of the firearmwithout leaving any residue therein. Said projectile comprises a body ofsubstantially cylindro-ogival shape having a propellant cavity therein,priming means in said propellant cavity, and an outer, peripheral flangeat the rear, terminal end of said body and integral therewith. Themaximum outer diameter of the body is equal to, or slightly less thanthe diameter of said bore across the lands defined between the helicalgrooves; and the outer diameter of said rear peripheral flange is largerthan the diameter of the bore across said lands. When the projectile isfired and impelled through the bore, the rear peripheral flange isdeformed or extruded by the walls of the chamber and the projectile bodyexpands under the pressure of firing and engages the lands in the bore,thus causing the projectile to spin while it travels through the bore.

The firearm chamber according to the invention is detachably mounted inthe breech of the firearm and comprises a tubular body having an innerdiameter equal to the diameter of the bore across the lands defined bythe helical grooves. One end of the tubular body abuts against the baseof the barrel, and the other end has an annular recess adapted toreceive and retain the peripheral flange at the rear end of the abovementioned projectile.

The firearm chamber of the invention differs from known chambers in thatits inner diameter is equal to the diameter of the bore in the barrelacross the lands defined by the helical grooves and therefore, it can beused only for firing a projectile having an outer diameter equal orslightly less than the diameter of the bore across the lands.Conventional amunnition, i.e., of the type having a case and a bulletfitted at the mouth of the case, cannot be fired from a chamberaccording to the invention, because if the case fits the chamber, thebullet would be undersized with respect to the bore. Consequently gasleakage would occur since the required compression could not be attainedand, furthermore, it would not be possible to obtain gyroscopicstability of the trajectory of the projectile.

The fact that the chamber is detachably mounted in the breech of thefirearm and independent from the barrel, permits manufacturing it from ametal having different characteristics than the metal forming otherparts of the firearm, and to replace the chamber or the barrel if one ofthem should become worn or damaged.

In addition, a detachable chamber simplifies considerably the operationof making the rifling or helical grooves in the barrel bore, since therifling could be made in a continuous length of tubing which can then besevered to form individual barrels.

Furthermore, the detachable chamber, permits independent machining,finishing and heat treating of the chamber and the barrel, whichfacilitates handling and obtaining high dimensional accuracy.

The invention will now be described with reference to the accompanyingdrawings in which:

FIG. 1 is an elevation view of a projectile adapted to be used with afirearm including a chamber according to the invention.

FIG. 2 is a longitudinal section of a firearm chamber according to theinvention.

FIG. 3 is a plan view of the chamber.

FIG. 4 is a longitudinal section, somewhat schematic, of a firearmindicating the location and arrangement of the firearm chamber. a

The firearm chamber of the invention is designed to fire self propelledballistic projectile such as shown in FIG. 1. This projectile comprisesa body 1, of substantially cylindro-ogival shape, having an outer,peripheral flange 2 at the rear, terminal end of the body.

The flange 2 is formed integrally with the projectile body and extendssubstantially at right angles with the longitudinal axis of theprojectile. The diameter and thickness of the flange 2 depend on thecalibre of th projectile.

With reference to FIG. 4, the firearm shown therein comprises a bolthousing 3 and a barrel 4. The barrel bore has a series of parallelgrooves 5 which spiral from the base to the muzzle end of the barrel anddefine land portions 6 therebetween.

The maximum outer diameter of the projectile body 1 is equal to orslightly less than the diameter of the bore across the lands 6.

As it can be best seen in FIGS. 2 and 3, the firearm chamber of theinvention, comprises a tubular body 7, having an inner diameter equal tothe diameter of the bore of the barrel across the lands defined by thehelical grooves 5. The forward end 8 of the chamber is adapted to abutagainst the base of the barrel, and the rear end 9, has an annularrecess 10 adapted to receive and retain the peripheral flange 2 at therear end of the projectile.

The recess 10 has an annular surface 10 perpendicular to thelongitudinal axis of the chamber, and a cylindrical wall 10'', coaxialwith the chamber. The diameter and depth of the recess 10 correspondswith the diameter and thickness of the projectile flange.

The chamber is housed in a bore 11 provided in the bolt housing 3 of thefirearm and rests on shoulder portions 12. The barrel has a threadedportion 4' which screws into the bolt housing 3 and is secured in placeby a locking nut 13. Thus, the chamber is retained between the barrel 4and the shoulder portions 12.

The rear end of the chamber is closed by a cylindrical lock 14 having apercussion pin 14'.

A projectile placed in the chamber, with its peripheral flange restingin the recess 10, is fired by percussion of the priming means of theprojectile (not shown) with the percussion pin '14. Upon firing, theprojectile is impelled through the chamber and its flange is deformed orextruded by the inner walls of the chamber.

. Almost simultaneously, the projectile body expands slightly under thepressure of firing and engages the lands in the bore thus causing theprojectile to spin while it travels through the bore.

As explained in the aforementioned copending patent application, therear flange 2 acts as a stop for the projectile in the chamber beforethe projectile is fired, and also as a sealing ring while the projectiletravels through the bore. As indicated, the projectile is totallyexpelled from the firearm without leaving any residue therein.

It will be obvious to those expert in the art that the size of thechamber, the thickness of the walls, and the depth and diameter of therecess 10, will depend on the calibre of the firearm.

While the invention has been described in connection with a specificembodiement thereof, it is to be understood that this is by way ofexample and not by way of limitation; and the scope of the appendedclaims should be construed as broadly as the prior art will permlt.

What is claimed is:

l. A firearm comprising a barrel including a bore having helical groovesand lands between said grooves, and a detachable chamber comprising atubular body having an inner diameter equal to the diameter of said boreacross the lands defined by the helical grooves. one end of said tubularbody abutting against the base of said barrel, and the other end havingan annular recess adapted to receive and retain a peripheral flange atthe rear end of a projectile adapted to be fired from said firearm.

2. A firearm chamber as claimed in claim 1 wherein said annular recesshas an annular surface substantially perpendicular to the longitudinalaxis of the chamber, and a cylindrical wall substantially coaxial withthe chamber.

3. In combination, a firearm barrel having a bore, said bore includinghelical grooves and lands between said grooves; a chamber comprising atubular body having an inner diameter equal to the diameter of said boreacross the lands defined by the helical grooves, one end of said chamberabutting againstthe base of said barrel, and the other end having anannular recess; and a self-propelled ballistic projectile. comprising abody of substantially cylindro-ogival shape and an outer peripheralflange at the rear terminal end of said projectile body; the annularrecess of said chamber being adapted to receive the peripheral flange ofsaid projectile; the outer diameter of the projectile body being at mostequal to the inner diameter of said chamher.

4. The combination in accordance with claim 3 wherein the outer diameterof the projectile body is slightly less than the inner diameter of saidchamber.

1. A firearm comprising a barrel including a bore having helical groovesand lands between said grooves, and a detachable chamber comprising atubular body having an inner diameter equal to the diameter of said boreacross the lands defined by the helical grooves, one end of said tubularbody abutting against the base of said barrel, and the other end havingan annular recess adapted to receive and retain a peripheral flange atthe rear end of a projectile adapted to be fired from said firearm.
 2. Afirearm chamber as claimed in claim 1 wherein said annular recess has anannular surface substantially perpendicular to the longitudinal axis ofthe chamber, and a cylindrical wall substantially coaxial with thechamber.
 3. In combination, a firearm barrel having a bore, said boreincluding helical grooves and lands between said grooves; a chambercomprising a tubular body having an inner diameter equal to the diameterof said bore across the lands defined by the helical grooves, one end ofsaid chamber abutting against the base of said barrel, and the other endhaving an annular recess; and a self-propelled ballistic projectile,comprising a body of substantially cylindro-ogival shape and an outerperipheral flange at the rear terminal end of said projectile body; theannular recess of said chamber being adapted to receive the peripheralflange of said projectile; the outer diameter of the projectile bodybeing at most equal to the inner diameter of said chamber.
 4. Thecombination in accordance with claim 3 wherein the outer diameter of theprojectile body is slightly less than the inner diameter of saidchamber.